1. Field of the Invention
This invention relates to tunnel-boring machines having rotary cutterheads and particularly to the anchoring system for such a machine including anchor shoes engageable with the tunnel wall aft of the rotary cutterhead.
2. Prior Art
Tunnel-boring machines utilizing rotary cutterheads in general are known, examples of such machines being shown particularly in FIGS. 15 and 16 of Robbins et al. U.S. Pat. No. 4,420,188, issued Dec. 13, 1983, and FIG. 1 of Turner U.S. Pat. No. 4,548,443, issued Oct. 22, 1985. The most similar machine is shown in Fikse U.S. Pat. No. 4,915,453, issued Apr. 10, 1990 and U.S. Pat. No. 5,005,911, issued Apr. 9, 1991. None of these machines, however, has an anchor shoe system of the type to which the present invention relates.